1. Field of the Invention
The present invention relates to a sheet stacking apparatus configured to stack a sheet, a sheet feeding apparatus, and an image forming apparatus.
2. Description of the Related Art
Conventionally, an image forming apparatus such as a printer and a copier includes a sheet feeding apparatus including a sheet feeding cassette, i.e., an sheet stacking apparatus, configured to be able to store (stack) a large number of sheets, and a feed roller for feeding the sheets stored in the sheet feeding cassette one by one to an image forming portion of the image forming apparatus. In general, such sheet feeding cassette is provided with a rear end restricting portion restricting a rear end, i.e., an upstream end in a sheet feeding direction in which the sheet is fed of the sheet, and a side end restricting portion restricting a widthwise position orthogonal to the sheet feeding direction of the sheet.
Here, Japanese Patent Application Laid-open No. H09-118439, for example, discloses a sheet feeding cassette including a press member provided in the rear end restricting portion and biased toward the sheet rear end by a biasing portion to position a front end of the sheet to a position where the sheet can be in contact with a sheet feeding roller.
The press member reliably abuts against the rear end of the sheet and a rear end position of the sheet can be thus accurately positioned by configuring such that the press member is biased to the rear end of the sheet as described above. However, there is a case where the rear end restricting portion is set downstream in the sheet feeding direction i.e., to a forward side of the cassette, of a normal position corresponding to a sheet size in trying to set the rear end restricting portion along the rear end of the sheet after placing a regular size sheets in the sheet feeding cassette. That is, there is a case where the rear end restricting portion is set while pushing the sheets placed in the sheet feeding cassette further without being locked at the position restricting the regular size sheet. In such a case, there is a possibility that the press member is pushed in while resisting against a bias force of the bias member and the rear end restricting portion is locked at the position where the press member is pushed in. In this case, the rear end of the sheet is pressed unnecessary by the rear end restricting portion and a front end of the sheet comes into pressure contact with a front wall surface of the sheet feeding cassette. That is, there arises a problem that the sheet is held tightly between the front wall surface of the sheet feeding cassette and the rear end restricting portion, causing a large friction force between the front end of the sheet and the sheet feeding cassette.